On 05/09/14 14:08, Rui Nuno Capela wrote:
On 2014-09-05 02:32, Kazakore wrote:
On 05/09/14 03:56, Rui Nuno Capela wrote:
On 09/04/2014 10:34 PM, Ralf Mardorf wrote:
This year You record an audio track with an I+O latency of 10.7 ms.
Two year later you want to restore this session, but you don't
remember
the jackd settings you used. Originally audio and MIDI tracks were in
sync, when you used 10.7 ms I+O latency. Within the years you got new
hardware, you don't remember what latency you once used and starts
jackd
with a lower I+O latency. Nothing bad would happen for Ardour
users, but
a Qtractor user would run into sync issues. Am I mistaken?
i really don't get why it would have worse or better sync depending
on jackd latency settings. please forgive me, but i don't see it
directly related to the case of audio vs. midi sync...
though, in the special case that comes to mind, iif the alsa-midi
timer is slaved to a pcm sound-device, as against to the system or
hires timer for instance, you probably will get it different whether
running on disparate buffer-sizes, periods and/or sample-rates,
that's for granted--well, if you change the sample-rate across
sessions you will get prompted to convert into a brand new and
different session anyhow ;)
byee
Huh??
So you have audio coming from the PC and MIDI going out to external
sound generating MIDI devices and you don't see how output latency
from the computer can affect the timing sync between sound from the
computer and sound from the audio modules??? Surely even a blind
wombat could see that! Unless there is some magic in Jack/AlsaMIDI
which automagically delays the MIDI by the same as the output buffer
settings of Jack. Then some might also want to add a fixed delay value
to take into account the hardware delay (propagation time) but I think
we really are getting a bit complex now!
re. external midi equipment, probably yes, that might be pertinent,
but...
my point was about audio and midi sync within qtractor (the sequencer)
internally. once midi gets out of the sequencer or even of the
machine, then i doubt one can ever compensate effectively for the
delay, drift or jitter that will be always present, no mater how small
but orthogonal to jackd buffer-size, periods or sample-rate, whatever,
and sure matters to a perfect sync. i doubt the output latency of the
in-machine jack-audio graph might be any significant or functional to
that goal.
I should probably drop out of this conversation as I haven't used
QTractor nor have I used any external gear for quite some time. But if
the issue is with external then you also need to bear in mind that you
might send some internally and some externally, so applying the same
delay to everything will still put some parts out of time with others. A
toggle for a MIDI channel going to int/ext could possibly be one solution??
Or if it is related to internal audio ssync I have to admit I am also
stumped why this would happen, as all audio coming out of the computer
would be going through the same audio buffers (Jack) and delayed the
same amount!
Although I very much doubt anybody would be able to hear the
difference if you're only talking a couple of ms and have different
sounds both internally and externally (same sounds would cause comb
filtering and eventually echo once latency became high enough.)
exactly :)
Plus (extrapolating from Ralf's comments) you clearly do already provide
a way for the adjustment to be done manually! Even if it is harder work
for the user...
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